Bài 2: (Đề 1)
$x+\frac{1}{2}=\frac{3}{4}$
$⇔x=\frac{3}{4}-\frac{1}{2}$
$⇔x=\frac{1}{4}$
Vậy $x=\frac{1}{4}$
$\frac{4}{5}x=\frac{4}{7}$
$⇔x=\frac{4}{7}:\frac{4}{5}$
$⇔x=\frac{5}{7}$
Vậy $x=\frac{5}{7}$
$8x=7,8x+25$
$⇔8x-7,8x=25$
$⇔\frac{1}{5}x=25$
$⇔x=25:\frac{1}{5}$
$⇔x=125$
Vậy $x=125$
Bài 2: (Đề 2)
$\frac{1}{2}-(\frac{2}{3}x-\frac{1}{3})=\frac{2}{3}$
$⇔\frac{2}{3}x-\frac{1}{3}=\frac{-1}{6}$
$⇔\frac{2}{3}x=\frac{1}{6}$
$⇔x=\frac{1}{4}$
Vậy $x=\frac{1}{4}$
$\frac{3}{x+5}=15\%$
$⇔\frac{3}{x+5}=\frac{3}{20}$
$⇔3x+15=60$
$⇔3x=45$
$⇔x=15$
Vậy $x=15$.
